Submission #112014

#	Time	Username	Problem	Language	Result	Execution time	Memory
112014		jangwonyoung	Duathlon (APIO18_duathlon)	C++14	0 / 100	198 ms	24312 KiB

count_triplets

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define pb push_back
const int N=1e5+1,M=2e5+1;
int n,m;
int d[N],low[N],vis[N];
vector<int>adj[N],ch[N];
int par[N],sz[N];
int ebc[N];
void dfs(int id,int p){
    vis[id]=true;
    sz[id]=1;
    d[id]=low[id]=d[p]+1;
    for(auto cur:adj[id]){
        if(cur==p){
            par[id]=p;continue;
        }
        if(vis[cur]){
            low[id]=min(low[id],d[cur]);continue;
        }
        ch[id].pb(cur);
        dfs(cur,id);
        sz[id]+=sz[cur];
        low[id]=min(low[id],low[cur]);
    }
}
ll val[N];
void dfs2(int id){
    if(low[id]<d[id]-1) ebc[id]=ebc[par[id]];
    else ebc[id]=id;
    int pcnt=1;
    for(auto cur:ch[id]){
        dfs2(cur);
        if(ebc[cur]!=ebc[id]) val[ebc[cur]]+=1LL*(n-sz[cur])*(n-sz[cur]);
        if(ebc[cur]!=ebc[id]) pcnt+=sz[cur];
    }
    val[ebc[id]]+=1LL*pcnt*pcnt;
}
ll ans;
int main(){
    ios::sync_with_stdio(false);
    cin >> n >> m;
    for(int i=1; i<=m ;i++){
        int u,v;cin >> u >> v;
        adj[u].pb(v);adj[v].pb(u);
    }
    dfs(1,0);
    dfs2(1);
    ans=1LL*n*(n-1)*(n-1);
    for(int i=1; i<=n ;i++){
        int pcnt=1;
        for(auto cur:ch[i]){
            if(ebc[cur]!=ebc[i]) ans+=1LL*(n-sz[cur])*(n-sz[cur]);
            if(ebc[cur]!=ebc[i]) ans-=val[ebc[cur]];
            if(ebc[cur]!=ebc[i]) pcnt+=sz[cur];
        }
        ans+=1LL*pcnt*pcnt;
        ans-=val[ebc[i]];
    }
    cout << ans << endl;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 11
• Subtask 3: 0 / 8
• Subtask 4: 0 / 10
• Subtask 5: 0 / 13
• Subtask 6: 0 / 15
• Subtask 7: 0 / 20
• Subtask 8: 0 / 8
• Subtask 9: 0 / 10